Turbulent Self-Assembly of a Magnetic Spot

by Axel Brandenburg 4 Jul 2013 Physics
Published in the "From the Institute" section of Nordita News issue 2, 2013

In the Nordita Newsletter of October 2011, we reported on the numerical detection of what is now referred to as negative effective magnetic pressure instability (NEMPI). This work has led to a number of new papers since then and, in particular, the award of a VR "breakthrough grant" to Nordita. One of the goals of this project is to underpin the recent suggestion that solar magnetic activity may be a shallow phenomenon and is not deeply rooted as is commonly believed.

In a recent preprint, members of the AstroDyn group at Nordita presented results of simulations that showed for the first time the self-assembly of a magnetic spot from just two ingredients: fully developed turbulence and strong density stratification. The picture above shows horizontal and vertical cross-sections through the magnetic spot. Future will show whether this also explains the spontaneous formation of sunspots.